Vulcanization of rubber



Patented Mar. 1, 1938 UNITED STATES VULCANIZATION OF RUBBER Marion W.Harman, Nitro, W. Va., assignor, by mesne assignments, to MonsantoChemical Company, Delaware St. Louis, Mo., a corporation of No Drawing.Application January 22, 1932, Serial No. 588,227

25 Claims.

The present invention relates to a process for vulcanization of rubberand similar products and to the products obtained thereby, and isparticularly directed to the acceleration of the vulcanization step byemploying in that step the reaction product of a mercaptoaryl-thiazole,for example an alkali metallic salt of mercaptobenzo-thiazole, and ahalogenated alkyl carbonyl containing compound.

It is preferred that the present class of accelerating materials beemployed in conjunction with a basic organic nitrogen containingaccelerating compound, preferably a guanidine, for example diphenylguanidine, to form a mixed accelerator.

One of the preferred class of compounds, for example the reactionproduct of mono chlor acetone and the sodium salt ofmercapto-benzothiazole, has been prepared according to the followingmanner:

Substantially 0.1 of a mol. (18.9 parts) of the sodium salt ofmercapto-benzo-thiazole was dissolved in a suitable solvent, for exampleparts by weight of ethyl alcohol, and substantially 0.1 of a mol. (9.3parts) of mono chlor acetone added slowly thereto at room temperature.After the reaction was complete, the sodium chloride formed was filtered01f and the filtrate added to a Weak alkaline solution, for examplesodium carbonate solution, whereupon, after filtering and washing thematerial thereby precipitated with water, a good yield of the preferredaccelerator was obtained in the form of a solid having a melting rangeof 64 to. 67 C.

The product prepared as described was incorporated in a typical gumstock and found to possess accelerating properties. Preferably, however,the material is employed in conjunction with a basic organic nitrogencontaining accelerating compound. Thus, a rubber stock was compounded inthe well known manner comprising Parts Pale crepe rubber Zinc oxide 5Sulfur 3 Diphenyl guanidine 0.6

The reaction product of substantially equimolecular proportions of monochlor acetone and the sodium salt of mercaptobenzo-thiazole 0.4

The rubber stock, after curing in a press in the well known manner, ontesting was found to possess the following modulus and tensilecharacteristics:

Table I Modulus of elasticity in Cure lbs/1n. at elongations oi TensileUltimate T libs. g k elgngaimc s cam ion mins per 300% 500% 700%lbs./1n.

sq. in.

, Percent 10 90 300 1660 1050 10 126 208 648 2360 950 20 179 403 16803605 860. 20 217 525 2210 4175 830 20 241 638 2700 4200 790 20 264 7563055 i705 780 The data set forth in Table I show that the preferredclass of accelerators when activated by a basic organic nitrogencontaining accelerating compound possess very desirable acceleratingproperties.

Another of the preferred class of rubber vulcanization acceleratorscomprises the reaction product of chloracetophenone andyamercaptobenzo-thiazole, for example the sodium salt ofmercapto-benzo-thiazole. One method whereby this material has beenprepared follows:

Substantially 0.1 mol. (18.9 parts) of the sodium salt ofmercapto-benzo-thiazole was dissolved in a suitable quantity of waterand substantially 0.1 mol. (15.4 parts) of chloracetophenone dissolvedin a small amount of an organic solvent, for example acetone, addedslowly thereto with cooling. The light yellow precipitate comprisingthe-reaction product was filtered off. and washed with an alkalinesolution so as to eliminate any unreacted mercapto-benzo-thiazole. Theproduct prepared in the manner described was obtained in good yield andmelted at 106 to 109 C. vThe reaction product of the sodium salt of.mercaptobenzo-thiazole and chloracetophenone when employed alone in atypical rubber stock was found to possess accelerating properties. It ispreferable, however, that said reaction product. be em,- ployed inconjunction with a basic organic nitrogen containing rubbervulcanization ;ac-

celerator. Thus a rubber stock was compounded in the well known mannercomprising 7 Parts Pale crepe rubber .100 Zinc oxide -1 5 Sulfur v 3Diphenyl guanidine a 0.6 The reaction product of substantiallyequimolecular proportions of chloracetophenone and the sodium salt ofmercapto-benzo-thiazole 0.4

The rubber stock thus compounded was vulcanized by heating in a press inthe well known manner, and the cured rubber stock after testing wasfound to possess the following tensile and modulus characteristics:

The data set forth in Table 11 show clearly that the preferred class ofcompounds form an important group of rubber accelerators when employedin conjunction with a basic organic nitrogen containing vulcanizationaccelerator to form a mixed accelerator.

The reaction product of substantially equimolecular proportions ofchloracetophenone and the sodium salt of mercapto-benzo-thiazole hasalso been employed in a tread stock.

As other examples of the preferred class of accelerating compounds, thefollowing materials have been prepared in a manner similar to thathereinbefore set forth.

(a) Reaction product of substantially equimolecular proportions of thesodium salt of mercapto-benzo-thiazole and chloracetanilid having .amelting range of 113-121 C.

(1)) Reaction product of substantially equimolecular proportions ofchloracetamid and the sodium salt of mercapto-benzo-thiazole having amelting range of 142-144: C.

Reaction product of substantially equimolecular proportions of thesodium salt of mercapto-benzo-thiazole and chloracet-o-chloranilidehaving a melting range of l -118 C.

((1) Reaction product of substantially equimolecular proportions ofchloracet-p-nitranilide and the sodium salt of mercapto-benzo-thiazolehaving a melting range of 150-152 C,

(e) Reaction product of substantially equimolecular proportions ofchloracet-o-toluidide and the sodium salt of mercapto-benzo-thiazolehaving a melting range of 145-149 C.

All of the above materials have been employed alone, but preferably areemployed in conjunction with a basic organic nitrogen accelerator, in atypical rubber stock. As examples of their use in conjunction with a.basic organic nitrogen containing accelerator, each of the aboveaccelerators, (a), (b), (c), (d) and (6), were incorporated separatelyin a rubber stock comprising One of the preferred accelerators (a) to(e) inclusive Diphenyl guanidine On testing strips of the abovedescribed stocks, vulcanized by heating in a press for different periodsof time under temperatures given by differas rubber accelerators.

ent steam pressures, the tensile and modulus data obtained show that thepreferred accelerators (a) to (e) inclusive, described above exhibit theaccelerating properties of the class.

Other basic organic nitrogen containing vulcanization accelerators thandiphenyl guanidine have been employed in conjunction with the preferredclass of materials. Thus, diacetone amine and piperidine have beenemployed in a typical rubber stock in conjunction with the preferredclass of accelerators, for example, the reaction product ofsubstantially equi-molecular proportions of chloracetamid and the sodiumsalt of mercapto-benzo-thiazole, and found to be activators thereof.

Other mercapto-aryl-thiazoles than mercaptobenzo-thiazole may be reactedwith a halogenated alkyl carbonyl containing compound. Thus,mercapto-tolyl-thiazole, mercapto-xylyl-thiazole, mercapto-naphthiazoleand the like may be reacted with mono-chloracetone, dichloracetone,chlor methyl ethyl ketone, chloracetophenone, chloracetamide,chloracetanilid, chloracet-ochloranilide, chloracet-p-nitranilide,chloraceto-toluidide, chlor diethyl ketone and analogous compounds andthe reaction products employed Again, mercapto-benzothiazole, or a saltthereof, preferably an alkali metallic salt, may be reacted withchlormethyl ethyl ketone, dichlor acetone and chlor diethyl ketone andthe reaction products employed as rubber vulcanization accelerators.Furthermore, other basic organic nitrogen containing accelerators thanthose hereinbefore set forth may be employed in conjunction with thepreferred class of compounds as activators thereof. Thus, 2,4 diaminodiphenyl amine, diortho-tolyl-guanidine and the like may be so employed.

The foregoing examples are to be illustrative only and not at alllimitative of the invention. Other vulcanized products may be obtainedby employing other compounding ingredients and other proportions ofingredients than those particularly set forth in the examples given.

What is claimed is:

1. The process of treating rubber which comprises heating rubber andsulfur in the presence of a vulcanization accelerating productcomprising a reaction product of a mercapto-aryl-thiazole and a ketonecontaining a halogenated alkyl group as a. constituent thereof.

2. The process of treating rubber which comrises heating rubber andsulfur in the presence of a vulcanization accelerating productcomprising a reaction product of a mercapto-arylthiazole and ahalogenated aliphatic ketone as a constituent thereof.

3. The process of treating rubber which comprises heating rubber andsulfur in the presence of a vulcanization accelerating productcomprising a reaction product of a mercapto-benzothiazole and ahalogenated aliphatic ketone as a constituent thereof.

4. The process of treating rubber which comprises heating rubber andsulfur in the presence of a vulcanization accelerating productcomprising a reaction product of a mercapto-benzothiazole and monochloracetone as a constituent thereof.

5. The process of treating rubber which comprises heating rubber andsulfur in the presence of a vulcanization accelerating productcomprising a reaction product of an alkali salt ofmercapto-benzo-thiazole and mono chloracetone as a constituent thereof.

benzo-thiazole and a ketone containing a halogenated alkyl group and adiaryl guanidine vulcanization accelerator.

8. The process of treating rubber which comprises heating rubber andsulfur in the presence of a mixture of accelerators, said acceleratorscomprising a reaction product of a mercaptobenzo-thiazole and ahalogenated aliphatic ketone and a diaryl guanidine accelerator.

9. The process of treating rubber which comprises heating rubber andsulfur in the presence of a mixture of accelerators, said acceleratorscomprising a reaction product of a mercaptobenzo-thiazole and achloracetone and a diaryl guanidine vulcanization accelerator.

10. The process of treating rubber which comprises heating rubber andsulfur in the presence of a mixture of accelerators, said acceleratorscomprising a reaction product of a mercaptobenzo-thiazole and mono chloracetone and diphenyl guanidine.

11. The process of treating rubber which comprises heating rubber andsulfur in the presence of a mixture of accelerators, said acceleratorscomprising a reaction product of an alkali salt ofmercapto-benzo-thiazole and mono chlor acetone and diphenyl guanidine.

12. The vulcanized rubber product produced by heating rubber and sulfurin the presence of a vulcanization accelerating product comprising areaction product of a mercapto-aryl-thiazole and a ketone containing ahalogenated alkyl group as a constituent thereof. a

13. The vulcanized rubber product produced by heating rubber and sulfurin the presence of a vulcanization accelerating product comprising areaction product of a mercapto-aryl-thiazole and a halogenated aliphaticketone as a constituent thereof.

14. The vulcanized rubber product produced by heating rubber and sulfurin the presence of a vulcanization accelerating product comprising areaction product of a mercapto-benzo-thiazole and a halogenatedaliphatic ketone as a constituent thereof.

15. The vulcanized rubber product produced by heating rubber and sulfurin the presence of a vulcanization accelerating product comprising areaction product of a mercaptc-benzo-thiazole and mono chlor acetone asa constituent thereof.

16. The vulcanized rubber product produced by heating rubber and sulfurin the presence of a vulcanization accelerating product comprising areaction product of an alkali salt of mercaptobenzo-thiazole and monochlor acetone as a constituent thereof.

17. The vulcanized rubber product produced by heating rubber and sulfurin the presence of a mixture of accelerators, said acceleratorscomprising a reaction product of a mercapto-benzothiazole and a ketonecontaining a halogenated alkyl group and a guanidine vulcanizationaccelerator.

18. The vulcanized rubber product produced by heating rubber and sulfurin the presence of a mixture of accelerators, said acceleratorscomprising a reaction product of a mercapto-benzothiazole and a ketonecontaining a halogenated alkyl group and a diary] guanidinevulcanization accelerator.

19. The vulcanized rubber product produced by heating rubber and sulfurin the presence of a mixture of accelerators, said acceleratorscomprising a reaction product of a mercapto-benzothiazole and ahalogenated aliphatic ketone and a diaryl guanidine vulcanizationaccelerator.

20. The vulcanized rubber product produced by heating rubber and sulfurin the presence of a mixture of accelerators, said acceleratorscomprising a reaction product of a mercapto-benzothiazole and a chloracetone and a diaryl guanidine vulcanization accelerator.

21. The vulcanized rubber product produced by heating rubber and sulfurin the presence of a mixture of accelerators, said acceleratorscomprising a reaction product of a mercapto-benzothiazole and mono chloracetone and diphenyl guanidine.

22. The vulcanized rubber product produced by heating rubber and sulfurin the presence of a mixture of accelerators, said acceleratorscomprising a reaction product of an alkali salt ofmercapto-benzo-tlnazole and mono. chlor acetone and diphenyl guanidine.I

23. The process of treating rubber which comprises heating rubber andsulfur in the presence of a mixture of accelerators, said acceleratorscomprising a reaction product of a mercaptoaryl-thiazole and a ketonecontaining a halogenated alkyl group, and a basic organic nitrogencontaining accelerator as an activator thereof.

24. The vulcanized rubber product produced by heating rubber and sulfurin the presence of a mixture of accelerators, said acceleratorscomprising a reaction product of a mercapto-arylthiazole and a ketonecontaining a halogenated alkyl group, and a basic organic nitrogencontaining accelerator as an activator thereof.

25. The process which comprises incorporating within rubber avulcanizing agent, a basic accelerator and a compound of the formula andvulcanizing the mixture.

MARION W. I-IARMAN.

